So many corporate videos tell people the message that is trying to be conveyed instead of showing it. It's basic film school knowledge that the purpose of a video is to show a message, not just say it. Nothing is more effective, especially in today's society of marketing oversaturation, than a video that uses no words.
Not only does this method stand out from other marketing videos because it's different, it also crosses cultural and language barriers. Anyone can understand the message, without the need of a translation. The silence also forces the viewer to watch more carefully, focusing on the screen and therefore, on the message.